1. Field of the Invention
This invention relates to a photosensitive resin composition, more particularly to a photosensitive resin composition for a black matrix of a color filter. This invention also relates to a black matrix formed from the photosensitive resin composition, a color filter including the black matrix, and a liquid crystal display device including the color filter.
2. Description of the Related Art
In order to enhance contrast ratio and display quality of a liquid crystal display device, a black matrix is usually disposed in gaps formed among stripes or dots of a color filter so as to avoid reduction of the contrast ratio and color purity due to light leakage among the pixels. Conventionally, a vapor deposited film containing chromium or chromium oxide is used for forming the black matrix. However, there are problems of complicated process, costly material, etc. Therefore, it has been proposed to form the black matrix using a photosensitive resin composition via photo lithographic technology.
U.S. Pat. No. 7,449,281 B2 discloses a photosensitive resin composition used for forming a black matrix. The photosensitive resin composition includes an alkali-soluble resin, an ethylenically unsaturated compound, a photo-initiator, a solvent, and a black pigment. The coating uniformity and the sensitivity of the photosensitive resin composition as well as the heat resistance of the black matrix are enhanced. This is done by application of the alkali-soluble resin along with adjustment and monitoring of viscosity and solid content of the composition, and vapor pressure of the solvent.
Nevertheless, the photosensitive resin composition is susceptible to environmental factors such as temperature and tends to deteriorate while in storage. Moreover, the black matrix is often used in portable display devices which are usually operated at outdoor environment by users. High temperature caused by sunlight might result in deteriorated adhesion of the black matrix. The imaging quality of the portable display devices is therefore lowered.
In view of the aforesaid, it is desirable in the art to provide a black matrix having superior adhesion after heating and to provide a photosensitive resin composition with superior ageing stability for forming the black matrix.